Stainless steel handles from the catalog
A stainless steel handle is a knife handle, or a pair of handle scales, made of stainless steel: by worldstainless's definition, steel with a minimum of 10.5% chromium by mass. On a framelock, part of that handle is also the lock. Böker says "the framelock is part of the handle itself," and Kershaw says the lockbar "prevents the blade from closing."
On a framelock the handle carries the lock, so its material has a second job. Böker's framelock entry says the handle scales "are usually made from particularly hard metals such as titanium or stainless steel, because these materials offer adequate resistance to the blade when the knife is used." Buck calls the locking mechanism a section of the handle frame, and the lock bar entry follows how that bar meets the tang and wears.
Gerber's Paraframe I page lists "Frame lock handle design" with "open stainless steel handles," and Kershaw calls stainless steel "strong and attractive" as a handle material. Stainless against aluminum is a choice set out in aluminum vs stainless steel knife handles.
A stainless handle's look depends on more than the metal: worldstainless says the appearance of stainless steel "will depend on the way it is made and finished." Kershaw lists a "Bead-blasted finish" for the stainless handles of its retired Norad and Esteem, and the bead blast finish entry describes that surface.
A stainless handle's Handle row may say stainless alone or add a grade word, as in 2Cr13 stainless. Producers document some stainless types: Carpenter calls its CarTech 410 "the basic hardenable martensitic stainless steel," and ATI lists 410 among its "hardenable, straight-chromium stainless steels." No source cited here does that for 2Cr13, a grade to raise with the knife's maker. Böker's glossary warns that "even stainless steel can rust under adverse conditions," which holds for a handle too; does stainless steel ever rust sets out the conditions.